ABSTRACT: BACKGROUND: The aim of the present study was to compare the effects of 10 weeks resistance training in combination with either a regular diet (Ex) or a low carbohydrate, ketogenic diet (Lc+Ex) in overweight women on body weight and body composition. METHODS: 18 untrained women between 20 and 40 years with BMI [greater than or equal to] 25 kg*m-2 were randomly assigned into the Ex or Lc+Ex group. Both groups performed 60-100 min of varied resistance exercise twice weekly. Dietary estimates were based on two 4-day weighed records. Body composition was estimated using Dual Energy X-ray Absorptiometry. Fasting blood samples were analyzed for total-, HDL- and LDL-cholesterol, triacylglycerols, and glucose. RESULTS: 16 subjects were included in the analyses. Percentage of energy (En%) from carbohydrates, fat and protein was 6, 66, and 22 respectively in the (Lc+Ex) group and 41, 34, 17 in the Ex group. Mean weight change (pre-post) was -5.6 +/- 2.6 kg in Lc+Ex; (p<0.001) and 0.8 +/- 1.5 kg in Ex; (p=0.175). The Lc+Ex group lost 5.6 +/- 2.9 kg of fat mass (p=0.001) with no significant change in lean body mass (LBM), while the Ex group gained 1.6 +/- 1.8kg of LBM (p=0.045) with no significant change in fat mass (p=0.059). Fasting blood lipids and blood glucose were not significantly affected by the interventions. CONCLUSION: Resistance exercise in combination with a ketogenic diet may reduce body fat without significantly changing LBM, while resistance exercise on a regular diet may increase LBM without significantly affecting fat mass. Fasting blood lipids do not seem to be negatively influenced by the combination of resistance exercise and a low carbohydrate diet.